JP4007260B2 - Tapered roller bearing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tapered roller bearing, and more particularly to a tapered roller bearing with reduced torque loss.
[0002]
[Prior art]
A tapered roller bearing having an outer ring, an inner ring and a plurality of tapered rollers disposed between them is compact, can support a large radial load and axial load, and can be used at a high speed rotation. Widely used. However, compared to ball bearings, the torque loss at the sliding contact portion between the large end face of the tapered roller that exerts an axial load and the large collar face of the inner ring is large, and from the viewpoint of energy saving, the reduction of the torque becomes an issue. Yes.
[0003]
As shown in FIGS. 4 (a) and 4 (b), the tapered roller bearing (21) having reduced torque loss due to sliding contact has an outer ring (22), an inner ring (23) and a tapered roller (24). The roller (24) has a large end surface (25) formed in a conical shape, and the inner ring (23) has a large collar surface (26) formed on an inclined surface facing the roller large end surface (25). (Patent Document 1).
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 61-139310 [0005]
[Problems to be solved by the invention]
In the tapered roller bearing (21) described in Patent Document 1 above, a portion excluding the annular recess (27) provided in the inner ring (23) so as to have a stress distribution indicated by hatching in broken lines in FIG. However, when an axial load is applied, the tapered roller (24) is lifted on the large collar surface (26) of the inner ring (23) as shown in FIG. 4 (b). And has a stress distribution indicated by hatching in the broken line in FIG. That is, between the end (24a) on the small end surface side of the tapered roller (24) and the end on the small collar side (23a) of the raceway surface and the end of the roller large end surface (25) near the main body and the inner ring The two parts between (23) and the large brim surface (26) will exert a particularly large force (occurrence of edge load), and the bearing (21) will be prematurely seized and peeled off. There was a problem that it could not be fulfilled sufficiently. There is also a problem that it is difficult to adjust the preload and the gap.
[0006]
An object of the present invention is to provide a tapered roller bearing that solves the above-described problems, prevents premature seizure and peeling, and can reduce torque loss.
[0007]
[Means for Solving the Problems and Effects of the Invention]
A tapered roller bearing according to the present invention is a tapered roller bearing having an outer ring, an inner ring, and a plurality of tapered rollers disposed between them, wherein the large end surface of the tapered roller is a convex curved surface continuous with the tapered surface, and the inner ring is large. The collar surface is a concave curved surface corresponding to this curved surface, and the contact line between the tapered roller and the inner ring raceway is radially outward on the roller small end side and radially on the roller large end side with reference to the line passing through the cone center. It is characterized by being inside.
[0008]
The line passing through the cone center is a straight line obtained when the conical surface of the tapered roller and the raceway surface of the inner ring are not crowned. Matched to the cone center line.
[0009]
The convex curved surface of the tapered roller is, for example, a spherical surface with a constant curvature, but is not limited to a constant curvature, and may be composed of a plurality of spherical surfaces having different curvatures, Further, it may be a quadratic curve such as a hyperbola or a parabola, an exponential curve, etc. In short, it may be a continuous curve. The concave curved surface of the large collar surface of the inner ring corresponding to the roller large end surface is formed so as to have, for example, a curvature of 50 to 53% of the diameter of the spherical surface when the tapered roller curved surface is a spherical surface. The curved surface of the inner ring is not limited to a constant curvature, and may be a quadratic curve such as a hyperbola, an exponential curve, or the like, and may be a continuous curve like the roller large end surface. The large brim surface of the inner ring is a curved surface continuous with the conical inner ring raceway surface.
[0010]
The shape of the outer ring shoulder corresponding to the large end surface of the tapered roller is arbitrary, and it may be a curved surface corresponding to the shape of the roller large end surface, but the conical inner surface generally used for tapered rollers is also acceptable. The outer ring which it has can also be used as it is. Further, the shape of the inner ring on the small brim surface side is the same as the conventional one.
[0011]
According to the tapered roller bearing of the present invention, the large end surface of the tapered roller is a convex curved surface continuous with the tapered surface, and the large collar surface of the inner ring is a concave curved surface corresponding to this curved surface. However, the tapered roller does not move like the conventional tapered roller bearing, and the edge load hardly occurs. Therefore, torque can be reduced by load support by rolling / sliding contact at the curved surface portion, and stress distribution is continuous and edge loading is prevented, so that early seizure and peeling can be prevented. Also, preload and clearance can be adjusted easily.
[0012]
In addition, since the curved surface portion comes into rolling / sliding contact at a position shifted radially outward from the cone center line, the roller rotation speed generated by driving from the inner ring is faster than the linear contact portion. Since the contact line of the inner ring raceway is on the radially outer side on the roller small end side and radially inward on the roller large end side with respect to the cone center line as a reference, the small end side portion of the tapered roller is fast and has the same large end. It will turn slowly at the side part, and by setting this amount appropriately, it is possible to counteract the factors that make the rollers fall over and uneven rotation speed of the rollers, and it is possible to make an optimal preparation that brings about smooth rotation .
[0013]
The curved shape of the large end face of the tapered roller and the curved face shape of the large collar surface of the inner ring are appropriately set according to the dimensions and operating conditions of the bearing so as to reduce the slip component of both contact components and increase the rolling component. . Along with this, it is a matter of course that the contact angle, the height of the collar, and the like are appropriately changed.
[0014]
The convex curved surface of the roller large end surface is not particularly limited as described above, but is preferably a spherical surface. By making the curved surface into a simple spherical surface, the above effects can be obtained with less manufacturing effort.
[0015]
In addition, a recess may be formed at the boundary between the large collar surface of the inner ring and the raceway surface. This recess makes it possible to prevent interference in production and can also be used as a reservoir for lubricating oil, thereby maintaining the above effects and further improving manufacturability and lubricity Can be made.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right refer to the left and right in the figure.
[0017]
A tapered roller bearing (41) according to the present invention shown in FIG. 1 includes an outer ring (42), an inner ring (43), a plurality of tapered rollers (44) disposed therebetween, and a holding unit that holds the tapered rollers (44). (45).
[0018]
The tapered roller (44) has a conical main body portion (51) and a large end surface (52) provided at the right end portion thereof. The large end surface (52) of the tapered roller (44) is a convex curved surface that is continuous with the tapered surface of the main body portion (51). In this embodiment, the curved surface is a convex spherical surface.
[0019]
The inner ring (43) includes a conical raceway surface (53), a small brim surface (54) provided at the left end of the raceway surface (53), and a large brim provided at the right end of the raceway surface (53). Surface (55). The large brim surface (55) is a concave curved surface corresponding to the convex curved surface of the large end surface (52) of the tapered roller (44). In this embodiment, the cross-sectional shape of the large brim surface (55) is a concave arc surface continuous to the raceway surface (53).
[0020]
The outer ring (42) has a conical raceway surface (56). In this embodiment, the track of the portion corresponding to the convex curved surface of the large end surface (52) of the tapered roller (44) is also formed in a cone shape.
[0021]
A line L2 indicated by a two-dot chain line in FIG. 1 is a line passing through a cone center in a conventional tapered roller bearing designed so that the apex of the cone is gathered at one point (cone center) on the center axis of the bearing. In the tapered roller bearing of the present invention, the contact line L1 between the tapered roller (44) and the raceway surface (53) of the inner ring (43) intersects the cone center line L2 at a point P, and the cone center line L2 is crossed. As a reference, it is positioned radially outward on the roller small end side and radially inward on the roller large end side.
[0022]
According to the tapered roller bearing (41) formed as described above, the outer ring (42) and the inner ring (43) and the tapered roller (44) are in line contact so as to have the stress distribution shown by the hatching in FIG. is doing. When an axial load is further applied from this state, the convex curved large end surface (52) of the tapered roller (44) comes into contact with the inner ring large collar surface (55) having a concave curved surface corresponding thereto. The position of the tapered roller (44) in the axial direction is stable and hardly moves in the axial direction with respect to the inner ring raceway surface (53). Therefore, the same stress distribution is maintained. Thus, by supporting the load by rolling with a continuous stress distribution, the occurrence of edge load can be prevented. Further, the contact surface of the convex curved surface and the concave curved surface is not in sliding contact but in a rolling / sliding contact state in which the slip component is greatly reduced, so that a tapered roller bearing (41) having a greatly reduced torque loss is obtained. be able to.
[0023]
Further, the curved large end face (52) makes rolling / sliding contact at a position shifted radially outward from the cone center line L2, so that the roller rotation speed generated by driving from the inner ring (43) is the main body portion ( 51) The contact line L1 between the tapered roller (44) and the raceway surface (53) of the inner ring (43) is radially outward on the roller small end side with respect to the cone center line L2. Since the roller large end side is radially inward, the small end side portion of the tapered roller (44) rotates at a high speed and the large end side portion rotates at a low speed. Since the intersection and intersection angle between the contact line L1 and the cone center line L2 between the tapered roller (44) and the raceway surface (53) of the inner ring (43) can be changed, this value should be set appropriately. It is possible to counteract the factors that cause the rollers to fall over or cause the revolution speed of the rollers to be non-uniform, so that an optimum preparation that brings about smooth rotation becomes possible.
[0024]
FIG. 3 shows another embodiment of the tapered roller bearing (41) according to the present invention. The inner ring (43) has a conical raceway surface (53) and a concave curved large end surface (55). In addition, an annular recess (58) is formed to prevent manufacturing interference. Other configurations are the same as those of the embodiment shown in FIG. 1, and the same reference numerals are given to the same configurations, and the description thereof is omitted.
[0025]
According to the tapered roller bearing (41) shown in FIG. 3, the outer ring (42) and the inner ring (43) and the tapered roller (44) are in line contact so as to have the stress distribution shown by the hatched lines in the figure. ing. Due to the annular recess (58) formed in the inner ring (43), the stress in that portion of the inner ring (43) is zero, but the overall stress distribution is almost the same as in FIG. . When an axial load is further applied from this state, the inner ring large collar surface (55) in which the convex curved large end surface (52) of the tapered roller (44) has a concave curved surface corresponding thereto as in the first embodiment. Therefore, the position in the axial direction is stable and hardly moves in the axial direction with respect to the inner ring raceway surface (53). Therefore, the same stress distribution is maintained. In this way, the occurrence of edge load can be prevented, and a tapered roller bearing (41) with a greatly reduced torque loss can be obtained, and the raceway surfaces (53) of the tapered roller (44) and the inner ring (43) can be obtained. By changing the intersection point and the intersection angle between the contact line L1 and the cone center line L2, the optimum preparation that enables smooth rotation is also possible. The annular recess (58) formed in the inner ring (43) can be used as a lubricating oil reservoir, thus reducing torque loss by supporting the load with rolling due to continuous stress distribution. In addition, a tapered roller bearing (41) having excellent lubricity can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an upper half portion showing an embodiment of a tapered roller bearing of the present invention.
FIG. 2 is a view showing a stress distribution of the tapered roller bearing of the present invention.
FIG. 3 is a view corresponding to FIG. 2 showing another embodiment of the tapered roller bearing of the present invention.
FIG. 4 is a diagram showing a stress distribution of a conventional tapered roller bearing.
[Explanation of symbols]
(41) Tapered roller bearings
(42) Outer ring
(43) Inner ring
(44) Tapered roller
(52) Large end face
(55) Large brim
(58) Annular recess L1 Contact line L2 Cone center line

Claims (3)

In a tapered roller bearing having an outer ring, an inner ring, and a plurality of tapered rollers disposed therebetween,
The large end surface of the tapered roller is a convex curved surface that is continuous with the tapered surface, the large collar surface of the inner ring is a concave curved surface corresponding to this curved surface, and the contact line between the tapered roller and the inner ring raceway is a line that passes through the cone center. As a reference, a tapered roller bearing characterized by being radially outward on the roller small end side and radially inward on the roller large end side. 2. The tapered roller bearing according to claim 1, wherein the convex curved surface of the roller large end surface is a spherical surface. The tapered roller bearing according to claim 1 or 2, wherein a recess is formed in a boundary portion between the large collar surface and the raceway surface of the inner ring.

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